Die configuration for high temperature diecasting

ABSTRACT

A die casting die includes a shoe comprised of a first material and includes a pocket. An insert is arranged in the pocket. The insert is comprised of a second material that is different from the first material and the insert provides a contoured surface. A coating is on the contoured surface. The coating provides a cast part contour.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority to International Application No.PCT/US2014/014,900, filed Feb. 5, 2014, which claims priority to U.S.Provisional Application No. 61/766,334, filed on Feb. 19, 2013.

BACKGROUND

This disclosure relates to a die casting die and system used in hightemperature die casting.

Generally, die casting is a process that includes forcibly moving moltenmetal into a die cavity to form a desired shape. More particularly, theprocess includes the steps of forcing molten metal into the die,retaining the metal in the die until it solidifies, and removing thesolidified part from the die.

One of the largest challenges in die casting is developing die materialsand a die configuration in order to maximize die life while minimizingdie cost. Because die casting is performed at high temperatures, thermalmechanical fatigue can occur in the dies.

SUMMARY

In one exemplary embodiment, a die casting die includes a shoe comprisedof a first material and includes a pocket. An insert is arranged in thepocket. The insert is comprised of a second material that is differentfrom the first material and the insert provides a contoured surface. Acoating is on the contoured surface. The coating provides a cast partcontour.

In a further embodiment of any of the above, the first material has athermal conductivity between 12 W·m⁻¹K⁻¹ and 62 W·m⁻¹K⁻¹.

In a further embodiment of any of the above, the first materialcomprises steel.

In a further embodiment of any of the above, the second material has athermal conductivity above 350 W·m⁻¹K⁻¹.

In a further embodiment of any of the above, the second materialcomprises copper.

In a further embodiment of any of the above, the coating has a hardnessbetween 36 HRC and 62 HRC.

In a further embodiment of any of the above, the coating includes atleast one of a cobalt chromium alloy, a cobalt alloy, and ceramic.

In a further embodiment of any of the above, the shoe includes at leastone passage for circulation of fluid.

In another exemplary embodiment, a die casting system includes a firstdie including a first shoe comprised of a first material. The first shoeincludes a first pocket. A first insert is arranged in the first pocket.The first insert is comprised of a second material that is differentfrom the first material. The first insert provides a first contouredsurface, and a first coating on the first contoured surface. The firstcoating provides a first cast part contour. A second die includes asecond shoe comprised of the first material. The shoe includes a secondpocket. A second insert is arranged in the second pocket. The secondinsert is comprised of the second material. The second insert provides asecond contoured surface and a second coating on the second contouredsurface. The second coating provides a second cast part contour. Thefirst die and the second die are arranged to form a die cavity. Achamber is in fluid communication with the die cavity, and a plunger forinjecting a molten metal through the chamber into the die cavity.

In a further embodiment of any of the above, the first material has athermal conductivity between 12 W·m⁻¹K⁻¹ and 62 W·m⁻¹K⁻¹.

In a further embodiment of any of the above, the first materialcomprises steel.

In a further embodiment of any of the above, the second material has athermal conductivity above 350 W·m⁻¹K⁻¹.

In a further embodiment of any of the above, the second materialcomprises copper.

In a further embodiment of any of the above, the first and secondcoatings have a hardness between 36 HRC and 62 HRC.

In a further embodiment of any of the above, the first and secondcoatings comprise at least one of a cobalt chromium alloy, a cobaltalloy, and ceramic.

In a further embodiment of any of the above, at least one shoe containsat least one passage for the circulation of fluid.

In a further embodiment of any of the above, the die casting systemincludes a multiple of fluid lines attachable to the at least one fluidpassage. The multiple of fluid lines are connectable to a cooling fluidsource for fluid communication between the at least one shoe and thecooling fluid source.

In another exemplary embodiment, a method for die casting includesarranging a first die and a second die to form a cavity. The first dieincludes a first shoe comprised of a first material. The first shoeincludes a first pocket. A first insert is arranged in the first pocket.The first insert is comprised of a second material that is differentfrom the first material. The first insert provides a first contouredsurface and a first coating on the first contoured surface. The firstcoating provides a first cast part contour. The second die includes asecond shoe comprised of the first material. The shoe includes a secondpocket. A second insert is arranged in the second pocket. The secondinsert is comprised of the second material. The second insert provides asecond contoured surface and a second coating on the second contouredsurface. The second coating provides a second cast part contour. Themethod includes forcing molten metal into the cavity. The methodincludes retaining the molten metal in the cavity until the molten metalbecomes a solidified metal, and removing the solidified metal from thecavity.

In a further embodiment of any of the above, at least one shoe includespassages for circulation of fluid during the retaining step.

In a further embodiment of any of the above, the second materialcomprises copper.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure can be further understood by reference to the followingdetailed description when considered in connection with the accompanyingdrawings wherein:

FIG. 1 schematically illustrates a die casting system.

FIG. 2 schematically illustrates a die.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates an example die casting system thatincludes a die assembly 10 having a first die 12 and a second die 14that form a die cavity 16. The system further includes a chamber 18 influid communication with the cavity 16. A plunger 20 is used to forcemolten metal through the chamber 18 into the cavity 16. The molten metalis then retained in the cavity 16 until it becomes a solidified castmetal part. The cast part is then removed from the cavity 16.

The first die 12 includes a first shoe 22 having a first pocket 24. Afirst insert 26 arranged in the first pocket 24. In the example, thefirst insert 26 is a separate structure from, but removably affixed tothe first shoe 22. The first insert 26 provides a contoured surface 28.The contoured surface 28 is coated with a coating 30, which provides acontour of the part to be cast.

FIG. 2 schematically illustrates the second die 14. The second die 14includes a second shoe 32, the second shoe having a second pocket 34. Asecond insert 36 arranged in the second pocket 34. In the example, thesecond insert 36 is a separate structure from, but removably affixed tothe second shoe 32. The second insert provides a contoured surface 38.The contoured surface 38 is coated with a coating 40, which provides acontour of the part to be cast. The first shoe 22 and second shoe 32 arecomprised of a first material, and the first insert 26 and the secondinsert 36 are comprised of a second material. The first material isdifferent from the second material.

One of ordinary skill in the art would recognize that the systemdisclosed is not limited to having two dies with one insert in each die.For example, more than two dies could be implemented, as could more thanone insert in each die.

In an example embodiment, the first shoe 22 and the second shoe 32 arecomprised of a material having a thermal conductivity between 12W·m⁻¹K⁻¹ and 62 W·m⁻¹K⁻¹. Example materials in this range that could beused for the shoes 22, 32 include, but are not limited to, steel andsteel alloys. A steel or steel alloy die shoe will provide high strengthto the die while also acting as a heat sink.

The first insert 26 and the second insert 36 are comprised of a highlythermal conductive substrate having a thermal conductivity above 350W·m⁻¹K⁻¹. Example materials in this range that could be used for theinserts 26, 36 include, but are not limited to, copper and copperalloys.

The insert coatings 30, 40 are approximately 0.1 inches (2.54 mm) thickand are provided by a material having a hardness between 36 HRC and 62HRC. Materials in this range that could be used as the coatings 30, 40may be at least one of a cobalt chromium alloy, a cobalt alloy, andceramic. Coating the insert will provide a deposited hard faced layerthat will resist the thermal shock on the insert during injection. Thedisclosed configuration will transfer heat extremely quickly to the dieshoe, reducing the amount of stress on the inserts.

In the example, at least one of the shoes 22, 32 may include at leastone passage 42 for the circulation of fluid to regulate the temperatureof the die casting system. As illustrated in FIG. 1, the at least onepassage 42 may be connected to a fluid source by means of fluid lines46, 48 to create fluid communication between the fluid source 44 and theshoe 32. Fluid circulation through the fluid passage 42 or passages isto occur at least during the process of retaining the molten metalinside the cavity 16. An example of fluid that could be used to regulatethe temperature of the die casting system is oil at 600° F. It should benoted that the system is not limited to the disclosed type of fluid orfluid temperature. Multiple fluid passages are typically used.

By staggering the thermal conductivity of the die casting system as donein the example embodiment, the heat from the molten metal injected intothe die cavity 16 will be quickly transferred to the shoe 22, 32 andremoved by the hot oil, which will increase the life of the die insert26, 36. Furthermore, the preferred embodiment is constructed fromrelatively inexpensive materials. The wear surface of the die assemblyis a deposit coating 30, 40 that can be easily refurbished as necessary.

The system may be used in hot chamber and cold chamber die casting.Generally, the die casting process involves forcing molten metal intothe cavity 16 formed by dies 12, 14, retaining the metal until themolten metal solidifies into the desired cast part, and then ejectingthe solidified metal cast part from the die cavity 16. In the preferredembodiment, this process will include the circulation of fluid throughat least one passage 42 in at least one of the shoes 22, 32 in order toregulate the temperature of the die system. This circulation of fluidwill occur during the molten metal retention process, and may beimplemented during other steps as well.

Although an example embodiment has been disclosed, a worker of ordinaryskill in this art would recognize that certain modifications would comewithin the scope of the claims. For that reason, the following claimsshould be studied to determine their true scope and content.

What is claimed is:
 1. A die casting die comprising: a shoe comprised ofa first material and including a pocket; an insert arranged in thepocket, the insert comprised of a second material that is different fromthe first material, and the insert providing a contoured surface; and acoating on the contoured surface, the coating providing a cast partcontour.
 2. The die casting die in claim 1, wherein the first materialhas a thermal conductivity between 12 W·m⁻¹K⁻¹ and 62 W·m⁻¹K⁻¹.
 3. Thedie casting die in claim 2, wherein the first material comprises steel.4. The die casting die in claim 1, wherein the second material has athermal conductivity above 350 W·m⁻¹K⁻¹.
 5. The die casting die in claim4, wherein the second material comprises copper.
 6. The die casting diein claim 1, wherein the coating has a hardness between 36 HRC and 62HRC.
 7. The die casting die in claim 6, wherein the coating comprise atleast one of a cobalt chromium alloy, a cobalt alloy, and ceramic. 8.The die casting die in claim 1, wherein the shoe includes at least onepassage for circulation of fluid.
 9. A die casting system comprising: afirst die including a first shoe comprised of a first material, thefirst shoe including a first pocket, a first insert arranged in thefirst pocket, the first insert comprised of a second material that isdifferent from the first material, the first insert providing a firstcontoured surface, and a first coating on the first contoured surface,the first coating providing a first cast part contour; a second dieincluding a second shoe comprised of the first material, the shoeincluding a second pocket, a second insert arranged in the secondpocket, the second insert comprised of the second material, the secondinsert providing a second contoured surface, and a second coating on thesecond contoured surface, the second coating providing a second castpart contour, wherein the first die and the second die are arranged toform a die cavity; a chamber in fluid communication with the die cavity;and a plunger for injecting a molten metal through the chamber into thedie cavity.
 10. The die casting system in claim 9, wherein the firstmaterial has a thermal conductivity between 12 W·m⁻¹K⁻¹ and 62 W·m⁻¹K⁻¹.11. The die casting system in claim 10, wherein the first materialcomprises steel.
 12. The die casting system in claim 9, wherein thesecond material has a thermal conductivity above 350 W·m⁻¹K⁻¹.
 13. Thedie casting system in claim 12, wherein the second material comprisescopper.
 14. The die casting system in claim 9, wherein the first andsecond coatings have a hardness between 36 HRC and 62 HRC.
 15. The diecasting system in claim 14, wherein the first and second coatingscomprise at least one of a cobalt chromium alloy, a cobalt alloy, andceramic.
 16. The die casting system in claim 9, wherein at least oneshoe contains at least one passage for the circulation of fluid.
 17. Thedie casting system in claim 17, having a multiple of fluid linesattachable to the at least one fluid passage, the multiple of fluidlines connectable to a cooling fluid source for fluid communicationbetween the at least one shoe and the cooling fluid source.
 18. A methodfor die casting comprising: arranging a first die and a second die toform a cavity, the first die including a first shoe comprised of a firstmaterial, the first shoe including a first pocket, a first insertarranged in the first pocket, the first insert comprised of a secondmaterial that is different from the first material, the first insertproviding a first contoured surface, and a first coating on the firstcontoured surface, the first coating providing a first cast partcontour, the second die including a second shoe comprised of the firstmaterial, the shoe including a second pocket, a second insert arrangedin the second pocket, the second insert comprised of the secondmaterial, the second insert providing a second contoured surface, and asecond coating on the second contoured surface, the second coatingproviding a second cast part contour; forcing molten metal into thecavity; retaining the molten metal in the cavity until the molten metalbecomes a solidified metal; and removing the solidified metal from thecavity.
 19. The method of claim 18, wherein at least one shoe includespassages for circulation of fluid during the retaining step.
 20. Themethod of claim 18, wherein the second material comprises copper.